Hitachi, Ltd. (NYSE:HIT) today announced, as an addition to its grapic LCD controller/driver series lineup,
the HD66729 LCD controller/driver for LCD display systems in mobile communication products such as
digital cellular phones, PHS phones, and message pagers, capable of 105 x 68-dot graphic display*1 at 1.8 V
single-power-supply voltage operation. Sample shipments will begin on February 19, 1999 in Japan.
The HD66729 has an on-chip 5X step-up circuit that enables a large-screen LCD panel to be driven by a
single-power-supply voltage of 1.8 V, plus enhanced power management features including a programmable
voltage step-up ratio. These features make it possible to reduce the voltage and power consumption of the
end-product. The product lineup includes COG*2, COF*3, and TCP*4 mounting types to meet a variety of
users' needs.
With the rapid growth of the market for mobile communication products such as cellular and PHS phones,
there is a constant trend toward slimmer and lighter products, together with lower costs, and the overall
system voltage is decreasing year by year. Meanwhile, to meet the need for multifunctionality and higher
added value, it has also become necessary for the small LCD panels used in these products to provide a
large-screen-size graphic display capable of implementing additional functions such as information services
that include kanji messages and e-mail, and WWW contents, as well as the conventional phone number
display and directory functions.
Hitachi is currently mass-producing the HD66726, with a 96 x 42-dot display capability, as a graphic LCD
controller/driver offering dot matrix display and fixed character display (including alphanumeric and kana
characters) in a single-chip. The new HD66729 now enables LCD panels with a larger screen size to be
implemented at a lower voltage.
The current HD66726 can step-up the system power supply voltage by up to 4 times to generate the LCD
drive voltage. However, this means that the maximum LCD drive voltage in a system with a 1.8 V power
supply voltage is only 7.2 V, not enough to drive a large-screen LCD with a vertical size of around 65 to 68
dots.
In view of this, the new HD66729 includes a 5X step-up circuit capable of generating an LCD drive voltage
of up to 9 V in a system with a 1.8 V power supply voltage, making possible LCD displays with a vertical
size of up to 68 dots. This enables the overall system voltage to be reduced and drastically cuts the total
current dissipation of the system, allowing smaller, lighter batteries to be used.
In general, as the LCD vertical screen size (LCD drive duty) increases, so does the LCD drive voltage, with
an accompanying rise in current dissipation, but the HD66729 incorporates features to minimize these
increases.
An LCD drive duty setting from 1/8 to 1/68 can be programmed by software as desired, and the step-up
output multiplication factor and LCD drive bias ratio can also be controlled by software. For example, with
the 105 x 68-dot (1/68 duty) screen size in normal operation, use of the 5X step-up circuit enables LCD
drive to be carried out with a 9 V LCD drive voltage, and by performing software switching during system
standby periods to enable the 105 x 8-dot (1/8 duty) pictogram and icon display area to be driven at 3.6 V
using the 2X step-up circuit, it is possible to cut the LCD panel charge/discharge current by approximately
75%. In addition, since the LCD drive bias ratio can be adjusted by software, the bias ratio can be kept low
through the use of liquid crystal materials with excellent on/off transient characteristics in the system
configuration stage, thus enabling the LCD drive voltage itself to be reduced.
When only part of the screen is used for display, if the LCD drive duty is set low the display will be biased
toward the top of the screen when the LCD drive duty is set low. While the pictogram display on cellular
phones, etc., is at the top of the screen, in other systems the display is often in the center of the screen, and
therefore a centering display function is supported which shifts the LCD drive area to the center of the
display screen. This allows center-screen message, time, or calendar display to be selected while the system
is on standby.
A partial smooth scroll display function is also supported that allows the selection of fixed display of
pictograms only at the top of the screen in cellular phones, etc., while performing vertical smooth scrolling
of the rest of the display area.
With most cellular phones, the width of the set itself limits the horizontal display size to around 100 dots.
With the HD66729, the number of LCD driver outputs has been cut by stretching the horizontal display size
to a maximum of 105 dots, resulting in a chip size 20% smaller than previous products (Hitachi
comparison). This means lower costs and also, in the case of COG mounting, results in a slim chip shape,
with a width of only 2.52 mm, that enables the mounting glass area to be kept to a minimum.
For interfacing to a microcomputer, the HD66729 includes a high-speed synchronous serial interface and a
68/80-type 8-bit or 4-bit bus interface. Access to on-chip registers and RAM can be performed by
continuous high-speed writing, independently of the internal operating clock frequency, enabling fast data
transfer to be achieved even over a serial interface.
The mounting methods supported are COG mounting, in which the device is directly mounted face-down on
the LCD glass, COF mounting, in which the device is mounted face-down on a flexible film substrate, and
TCP mounting, in which the device is connected to the LCD glass via a heat seal.
Hitachi plans to extend the lineup in the future by developing models supporting even larger display sizes
and models supporting gray-scale display, based on the HD66729.
Notes: 1. Graphic display:
On-chip bit-mapped display RAM is provided, and the microcomputer can display arbitrary
patterns such as kanji and game patterns.
2. COG (Chip On Glass):
A mounting method in which a chip with a gold bump is directly mounted face-down on the
LCD glass.
3. COF (Chip On Film):
A mounting method in which a chip with a gold bump is directly mounted face-down on a
flexible film substrate.
4. TCP (Tape Carrier Package):
A package in which the chip is mounted on a thin-film tape. Ultra-thin type mounting is
possible.
< Typical Applications >
- Digital cellular systems (PDC, GSM, CDMA, etc.), PHS
- Digital cordless phones, fax machines
- Bidirectional pagers, kanji/Chinese-language pagers, electronic wallets, etc.
< Prices in Japan > (For Reference Only)
Product Code Display Size Shipment Form Mounting Form Sample Price (Yen)
HCD66729BP 105 x 68 dots Chip with gold bump COG, COF 450
HD66729TB0 105 x 68 dots Bent-lead TCP TCP 650 |
